Separation of cineoles from hydro



Patented Jan. 18, 1949 SEPARATION OF CARBONS OF CINEOLES FROM HYDRO-SIMILAR BOILING RANGE BY AZEOTROPIC DISTILLATION WITH PHENOLS Harold E.J ohnson,

Spurlin,

Wilmington, Marshailton, Del., assignors to Herand "Harold M.

cules Powder Company, Wilmington, De l., a I

corporation of Delaware No Drawing. Application February 6, 1947,

Serial No. 726.9

3 Claims. (Cl. 202-42) g This invention relates to a process forseparating the cineole and hydrocarbon constituents of a mixturecontaining cineoles and hydrocarbons of similar boiling range and, moreparticularly,

to a process of separating such constituents by fractional azeotropicdistillation.

In commercial processes for the production oi cineoles, a mixture ofhydrocarbons, mainly terpenes, also is usually formed concurrently withthe cineoles, resulting in a product containing both hydrocarbons andcineoles. The presence of these hydrocarbons, which as a mixture rangein boiling point from about 172 to 190 (3., complicates isolation of thepure cineoles since the latter have boiling points within thehydrocarbon range. 1,4-Cineole has a boiling point of about 171-2 C. and1,8-cineole of about I'M-5 (7., consequently conventional fractionaldistillation procedures have not been successful in efllclentlyseparating the cineoles from the components of the mixture ofhydrocarbons. Various methods have been proposed, however, for eflectingthe separation of cineoles and hydrocarbons of similar boiling range,and the more successful methods have involved distillation of acineole-hydrocarbon mixture in the presence of certain cresols. Thecineoles form stable complexes with the mand p-cresols at lowtemperatures and pressures, and it therefore has been possible bymaintaining sufficiently low temperatures and pressures to distill offthe more volatile hydrocarbons. These methods have been somewhatdisadvantageous, however, due to the fact that atmospheric pressurescould not be utilized. At atmospheric pressures and the concurrentlyhigher temperatures necessary to distill the hydrocarbons thecineole-cresol complexes are not stable. consequently the cineoles arenot prevented from distilling with the hydrocarbons. These methods alsohave been disadvantageous in not being able to use phenol as thecomplex-forming agent, the boiling point of phenol being too close tothat i of any of the cineoles and hydrocarbons to permit formation ofstable complexes with the cineoles.

, Now in accordance with this invention, it has been found that phenolmay be utilized to separate the cineole and hydrocarbon constituents ofa mixture containing cineoles and hydrocarbons of similar boiling rangeby subjecting the mixture of cineoles and hydrocarbons to fractionalazeotropic distillation in the presenceoi phenol as the azeotropicagent. In contrast with i previous processes, which have not used aphenolic compound such as phenolto form co'n 'sta-nt boiling azeotropicmixtures, phenol is used in the process in accordance with thisinvention for the purpose of forming constant boiling mixiures with thecineoles and the hydrocarbons contained in a mixture composed of thecineoles and hydrocarbons of similar boiling range. It also has beenfound in accordance with this invention that the azeotropic mixtureswhich phenol forms with 1,4-cineole, l,8cineole, and the hydrocarbons ofsimilar boiling range may be separated into their individual componentsby subjecting each azeotropic mixture to fractional steam distillation.

In carrying out the process in accordance with this invention, phenoland a cineole-hydrocarbon mixture in which the cineole content mayb63101 example, about are charged pot fitted with a packed column havingabout theoretical plates. The reaction mixture then is heated todistillation temperatures and fractional distillation carried out. Thisresults in the separation of tures; namely, hydrocarbon-phenol,1,4-cineolephenol, and 1,8-cineole-phenol, the hydrocarbons formingminimum boiling azeotropes with the phenol and the cineoles formingmaximum bolling azeotropes with'the phenol. In the case of the maximumboiling cineole-phenol azeotropes, the 1,8-cineole-phenol azeotropeboils higher than does the 1,4-cineole-phenolazeotrope. Followingseparation of the individual hydrocarbon-phenol, 1.4-cineole-phenol and1,8-cineole-phenol azeotropes, each is subjected to fractional steamdistillation for the purpose of recovering the hydrocarbons, the1,4-cineole, and the Lil-cineole, respectively.

The following examples constitute specific embodiments of the process inaccordance with this invention. All parts are parts by weight.

Example 1 To a heating pot fitted with a 75-plate packed column wascharged 1516 parts of phenol. The phenol was distilled to a constanttemperature of 120.1 C. at an absolute pressure of mm. of mercury, thenthere were added to the heating pot 2364 parts of acineole-hydrocarbonmixture in which the cineole content was 55%, and an three mainazeotropic mix-' column amounted to the pressure drop of 10 mm. ofmercury. Through the additional 1240 parts of phenol. Normally. both thecineole-hydrocarbon mixture and the total amount of phenol may beinitially added together, but in the present case the vapor temperatureof the phenol was used as a basis for do the existence of maximumboiling azeotropes. The combined phenol-cineole-hy'drocarbon mixturethen was distilled batchwise at a reflux ratio of approximately 76 to 1,and 0.5% fractions were removed as overhead product throughout thecourse of the distillation. The pressure was maintained at 100 mm., andthe maintained at a constant pressure drop of 16 mm.

of mercury. N

The various 0.5% hydrocarbon-phenol fractions boiled over a range of83.6 to 110 C. at a pressure of 100 mm.. and when combined on the basisof boiling point and refractive index represented a total fraction of1460.3 parts. likewise, the 1,4-cineole-phenol over a range 01 119.3 to120 C. at a pressure of 100 mm. and on combination represented a totalfraction of 2039.2 parts. The 1,8-cineole-phenol azeotrope fractionsboiled over a range 121 to 121.2 C. at a pressure of 100 mm. and oncombination represented a total fraction. of 1369.2 parts. The residueremaining in the heating pot amounted to 148, parts and that remainingin the 43 parts, the total residue of the total charge. Adistillaincurred during the disconstituting 3.8% tion loss of 0.6% wastillation.

Example 2 Following the general procedure utilized in Example 1, 1001parts of the cineole-hydrocarbon mixture of Example 1 and 600 parts ofphenol were charged to the heating pot and fractionally distilled. Areflux ratio of 7-5 to 1 wasused. the column pressure was maintained at100 mm. and throughput was maintained at a constant course of thedistillation 1.5% fractions were removed as overhead product. Thefractions were recombined on the basis of boiling point and refractiveindex. Since the amount of phenol utilized was suflicient to removecompletely as their azeotropes the hydrocarbons and the 1,8-cineole, butinsuilicient to remove completely as its azeotrope the 1,4-cineole, thefour fractions collected constituted the hydrocarbo -phenol azeotrope,1,4-cineole, the 1,4-cineole-phenol azeotrope, and the1,8-cineole-phenol azeotrope. The hydrocarbon-phenol az'eotropedistilled over a range of 88 to 105 C. at 100 mm. and represented 268.0parts. The 1,4-cineole fraction distilled between 105 and 106 467.8parts. The 1,4-cineole-phenol azeotrope distilled between 118 and 119 C.at 100 mm. and represented 338.4 parts. The 1,8-cineole-phenol azeotropefractions distilled over a temperature range of 119 to 121 C. at 100 mm.and constituted 468.4 parts. A total of 43 parts residue was collectedfrom the heating pot and column and represented 3.2% of the totalcharge. A distillation loss of 0.9% was incurred.

Example 3 To a heating rpot fitted with a 20-plate column containing anautomatic separatory head was charged 424 parts of the1,8-cineo'le-phenol azeotrope obtained in Example 2. The cineole-phenolazeotrope contained in the heating pot was subjected to steamdistillation at atmospheric pressure, the temperature being 97 C. Duringthe throughput was.

azeotrope fractions boiled distillation the water condensate in theseparatory head was kept 'at total reflux and the 1,8-cineole layer wasdistilled at a reflux ratio of approximately 13 to 1. There wasrecovered 136.! parts of 1,8-cineole which had a refractive index of1.4573 at C. and was essentially 100% ure. The 1,8-cineole had a boilingpoint of 107.9" C. at'100'mmz, a density of 0.92584 at20 C., and acongealing point of 1.5 C. By calculation from ultraviolet absorptionanalysis 33% of the 1,8- clneole-phenol azeotrope was 1,,8-cineole. thisbasis 97.7% of the 1,8-cineole estimated to be in the phenol -azeotropewas recovered.

Example 4 Following the procedure of Example 3, 744 parts of the1,4-cineole-phenol azeotrope obtained in Example 1 was fractionallysteam distilled at a.-

mdspheric pressure, the temperature being 98 C.

Throughout the distillation approximately 1.5% fractions of 1,4-cineolewere removed overhead.

'These fractions had a constant reiractive index invention has beenillustrated by the examples in connection with. a cineole-hydrocarbonmixture C. at 190 mm. and represented containing 55% cineoles, theamount or cineoies in relation to the hydrocarbons may be variedconsiderably. The process may be utilized with any cineole-hydrocarbonmixture, but it generally is more applicable to cineole-hydrocarbonmixtures contaimng from about 15 to about total cineoles. From practicalconsiderations the range of cineole content should be from about 50 toabout 75%. Also, although the cineole-nydrocarbon mixture used in theexamples contained both 1,4-cineole and 1,8-cineole, the process isoperable with cineole-hydrocarbon mixtures containing only one of thecineoles. Such mixtures are obtained, for example, by the partialdehydration of either 1,4-terpin or 1,8-terpin for the purpose ofobtaining 1,4-cineole or 1,8-cineole, respectively.

In carrying out the fractional azeotropic dishave shown the use of about1.2 parts and about 0.6 part, respectively, phenol, per part of thecineole-hydrocarbon mixture. In general however; the parts by weightratio of phenol to the mixture containin \cine'oles and hydrocarbons ofsimilar boiling range may be from about 0.3:1 to about 4:1. A desirablerange upon this basis is from about 0.3:1 to about 0.6:1, preferablyfrom about 0.3 1 to about 0.5 1, in case it is desired to effect thetype of separation shown in Example 2. In this example there wassufflcient phenol to remove completely as constant boiling azeotropesthe hydrocarbons and the 1,8- cineole, but insumcient phenol to removecompletely as its azeotrope the 1,4-cineole. The latter was thereforepermitted to distill partially as its azeotrope and partially as free1,4-cineole. It

is possible by decreasing further the amount of phenol used in Example 2to separate the 1,4-

cineole only as free 1,4-cineole. This generallyof 1,4-cineole. The 1,4-

C. and an 0f the azeotropic agent,

. with phenol. the partsby between the two though the temperaturediilerential between the of such a process depends upon the fact that1,4- cineole forms a more unstable azeotrope with phenol than does1,8-cineole, and that in the presence of a relatively insuflicientamount of phenol will not form a phenol azeotrope. This modification ofthe process effects a saving in the amount of phenol necessary and isadvantageous for obtaining pure 1,8-cineole since a wide temperatureestablished between the boiling point of the 1,8-cineole-phenolazeotrope and the boilin points of the hydrocarbon-phenol azeotrope andof 1.4-cineole.

In case, as in Example 1, however, it is desired to distfll both of thecineoles as well as the hydrocarbons in the form of their respectiveazeotropes s a range of about 0.3-:1 to about 0.5:1. Operation thisinstance being from about 3:1 to about 4:1. With this amount oi phenolthere is an eifective working temperature diil'erential of about to C.between the minimum boiling hydrocarbonphenol azeotrope and the maximumboiling cineole-phenol azeotropes, and there also is an operatingtemperature differential of about 1.2 C.

cineole-phenol azeotropes. Al-

two cineole-pheno1 azeotropes is rather small, this is compensated bythe diiference in composition of the two azeotropes. 1,4-cineole-phenolazeotrope contains approximately 50% 1,4-cineole and the1,8-cineole-phenol azeotrope contains about 33% 1,8-cineole, completeseparation of the two azeotropes is possible in an efllcient columnoperating at a temperature differential of 1.2 0. Columns having about75 to about 200 theoretical plates are satisfactory, particularly whenoperated at a reflux ratio between about 75:1 to about 150:1, preferablybetween about 7521 to about 90:1.

In the examples the azeotropic distillations with phenol were carriedout at an absolute pressure of 100 mm. of mercury.

atmospheric pressures and, tropic distillation may be carried outbetween about and about 760 mm. of mercury. A pref. erable range isbetween about 75 and about 250 mm. of mercury, and a particularlyapplicable range is between about 100 and about 200 mm. oi mercury. Y

As shown in Examples 3 and 4 the cineole- .phenol azeotropes may bebroken by subjecting them to fractional steam distillation. Such aprocess also may be utilized to separate the components of thehydrocarbon-phenol azeotrope. In the fractional steam distillation ofthe 1.8- cineole-phenol azeotrope, for example, there is formed anazeotropic distillate composed of water, phenol, and 1.8-cineole.. Inthe fractionating column, which is equipped with an automatic separatoryhead adapted to separate the 1,-8- cineole and water phases and returnthe latter downward through the column to the distillation pot, as thecineole-water-phenol azeotrope ascends. the phenol is extracted from theazeotrope and washed down the column by the hot water returning from theseparatory head. Following extraction of the phenol, the residualmixture of water and 1,8-cineole ascends the column and is separatedinto its components in the separatory head, the Lil-cineole beingwithdrawn under minimum reflux ratio conditions.

The process in accordance with this invention eflective separation ofthe two cineoles from each other. The cineoles recovered according tothe process of this invention are of a higher state of purity than ithas been possible to obtain by previous processes. In contrast to priormethods for effecting separation of cineoles from hydroboiling range,the present process may be operated at atmospheric pressures and theconcurrently higher temperatures.

E. Johnson.

What we claim and desire to protect by Letters Patent is: I

tlon with water reflux.

2. The prpcess'of separating the cineole and hydrocarbon constituents ofa mixture containing 1,4-cineole, 1,8-cineole and hydrocarbons ofsimilar boiling range said mixture to fractional azeotropic distillationfrom about 0.3:1 to about 0.5:1, recovering as separate fractions thehydrocarbon-phenol azeotrope, 1,4-cineole, and the 1,8-cineole-phenolazeotrope. and subjecting the hydrocarbon-phenol and 1,'8-cineole-phenolazeotropes each individually to free ional steam distillation with waterreflux.

3. The process of separating the cineole and hydrocarbon constituents ofa mixture containing 1,4-clneo1e, 1,8-cineole and hydrocarbons of simiarboiling range which comprises subjectproduce is obtained under the whichcomprises subjecting memes water reflux.

HAROLD E. JOHNSON. HAROID M. SPURLIN.

8 REFERENCES man The toilowin: references are of record inihe me o!.thie potent:

UNITED STATES PATENTS Number Name Date 2,090,062 Bibb Aug. 24, 19372,815,986 Scrutchfleld Apr. 6, 1943 2,353,319

Sheffield July 11, 19M

